鼠标滚轮事件和Mac触控板双指事件

// creates a global "addWheelListener" method
// example: addWheelListener( elem, function( e ) { console.log( e.deltaY ); e.preventDefault(); } );
(function(wdow,document) {

    var prefix = "", _addEventListener, onwheel, support;

    // detect event model
    if ( wdow.addEventListener ) {
        _addEventListener = "addEventListener";
    } else {
        _addEventListener = "attachEvent";
        prefix = "on";
    }

    // detect available wheel event
    support = "onwheel"  document.createElement("div") ? "wheel" : // 各个厂商的高版本浏览器都支持"wheel"
              document.onmousewheel !== undefed ? "mousewheel" : // Webkit 和 IE一定支持"mousewheel"
              "DOMMouseScroll"; // 低版本firefox

    wdow.addWheelListener = function( elem, callback, useCapture ) {
        _addWheelListener( elem, support, callback, useCapture );

        // handle MozMousePixelScroll  older Firefox
        if( support == "DOMMouseScroll" ) {
            _addWheelListener( elem, "MozMousePixelScroll", callback, useCapture );
        }
    };

    function _addWheelListener( elem, eventName, callback, useCapture ) {
        elem[ _addEventListener ]( prefix + eventName, support == "wheel" ? callback : function( origalEvent ) {
            !origalEvent && ( origalEvent = wdow.event );

            // create a normalized event object
            var event = {
                // keep a ref to the origal event object
                origalEvent: origalEvent,
                target: origalEvent.target || origalEvent.srcElement,
                type: "wheel",
                deltaMode: origalEvent.type == "MozMousePixelScroll" ? 0 : 1,
                deltaX: 0,
                deltaZ: 0,
                preventDefault: function() {
                    origalEvent.preventDefault ?
                        origalEvent.preventDefault() :
                        origalEvent.returnValue = false;
                }
            };
            
            // calculate deltaY (and deltaX) aordg to the event
            if ( support == "mousewheel" ) {
                event.deltaY = - 1/40  origalEvent.wheelDelta;
                // Webkit also support wheelDeltaX
                origalEvent.wheelDeltaX && ( event.deltaX = - 1/40  origalEvent.wheelDeltaX );
            } else {
                event.deltaY = origalEvent.detail;
            }

            // it's time to fire the callback
            return callback( event );

        }, useCapture || false );
    }

})(wdow,document);

function wheelEvent (e) {
    if (Math.abs(e.deltaX) !== 0 && Math.abs(e.deltaY) !== 0) return console.log('没有固定方向');
    if (e.deltaX < 0) return console.log('向右');
    if (e.deltaX > 0) return console.log('向左');
    if (e.ctrlKey) {
        if (e.deltaY > 0) return console.log('向内');
        if (e.deltaY < 0) return console.log('向外');
    } else {
        if (e.deltaY > 0) return console.log('向上');
        if (e.deltaY < 0) return console.log('向下');
    }
}

ctrlKey: origalEvent.ctrlKey || false,